Frac Plug Having a Cover

ABSTRACT

A frac plug having a cover and including one or more expansion components configured to expand during setting of the frac plug within a section of a tubular disposed in a wellbore. The cover may be disposed circumferentially about at least the one or more expansion components of the frac plug. The cover may be configured to prevent the one or more expansion components from expanding during deployment of the frac plug in the tubular and to permit the one or more expansion components to expand during setting of the frac plug in the tubular.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application having Ser. No. 62/621,076 which was filed Jan. 24, 2018. The aforementioned patent application is hereby incorporated by reference in its entirety into the present application to the extent consistent with the present application.

BACKGROUND

In oil and gas production, it is sometimes beneficial to stimulate a reservoir by pumping in high pressure fluids and particulates, such as sand. In order to do this, one or more tubular sections of a tubular (e.g., casing) installed in the well may need to be isolated for a period of time and re-opened so the well can be produced. Some current methods of isolation use a frac plug and a sealing ball. A frac plug is a hollow, cylindrical plug that can be installed in the tubular section(s) selected for isolation within the well. The sealing ball then seats in the frac plug to stop fluid flow through the frac plug location and isolate the selected tubular section(s).

Currently, frac plugs are built around a central mandrel. Typically, the central mandrel is then held in place within a tubular section using upper and lower slips that are expanded to grip the inner wall (commonly referred to as the inner diameter) of the tubular section during setting of the frac plug. In addition, one or more sealing members of the frac plug may be expanded during setting of the frac plug to place the frac plug in a sealing relationship with and to isolate the tubular section. To set the frac plug within the tubular section, the frac plug as part of a bottom hole assembly (BHA) is deployed or run in the tubular at a speed capable of reaching upwards of 800 ft/min. At such speed, expandable components of the frac plug (e.g., slips, sealing members, etc.) may begin to expand outward, and in some instances, may contact the inner diameter of the tubular, thereby causing the BHA to stop and become stuck in the tubular.

Accordingly, it is desirable to secure the expandable components of the frac plug to prevent the premature expansion thereof and the sticking of the BHA in the tubular during deployment. One known manner of securing the expandable components of the frac plug is the wrapping of wire or fishing line around the slips of the frac plug to prevent the slips from expanding during deployment. However, it has been found that the wire or fishing line may break prematurely or may get snagged by or caught on a protrusion extending from the tubular during deployment, resulting in the breakage of the wire or fishing line and the premature expansion of the frac plug and sticking of the BHA in the tubular.

What is needed, therefore, is a frac plug including a device capable of securing the expandable components of a frac plug during deployment thereof in a tubular to prevent the expandable components from prematurely expanding and causing the BHA to become stuck in the tubular prior to setting the frac plug in the tubular.

SUMMARY

Embodiments of the disclosure may provide a frac plug having a cover and including one or more expansion components configured to expand during setting of the frac plug within a section of a tubular disposed in a wellbore. The cover may be disposed circumferentially about at least the one or more expansion components of the frac plug. The cover may be configured to prevent the one or more expansion components from expanding during deployment of the frac plug in the tubular and to permit the one or more expansion components to expand during setting of the frac plug in the tubular.

Embodiments of the disclosure may further provide a method for setting a frac plug within a tubular section. The method may include covering at least one or more expansion components of the frac plug with a cover. The method may also include disposing the frac plug on a running tool. The method may also include positioning the frac plug within the tubular section using the running tool. The method may further include compressing the frac plug with the running tool such that the cover is segmented and the one or more expansion components engage with the tubular section, retaining the frac plug in position within the tubular section.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 illustrates a side view of an exemplary frac plug, according to one or more embodiments disclosed.

FIG. 2 illustrates a side view of the frac plug of FIG. 1 with a cover disposed circumferentially about a portion of the frac plug.

FIG. 3 illustrates a side view of the frac plug of FIGS. 1 and 2 in a set position, where the cover has been segmented.

FIG. 4 illustrates a side view of the frac plug of FIG. 1 with a cover disposed circumferentially about substantially all of the frac plug.

FIG. 5 illustrates a side view of the frac plug of FIGS. 1 and 4 in a set position, where the cover has been segmented.

FIG. 6 is a flowchart depicting a method for setting a frac plug within a tubular section, according to one or more embodiments disclosed.

DETAILED DESCRIPTION

It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.

Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein.

FIG. 1 illustrates an exemplary frac plug 100, according to one or more embodiments disclosed. The frac plug 100 may include a plug body 101 that includes a first sub 102 and a second sub 104 theadingly engaged with one another. Alternative embodiments of the frac plug 100 may instead include a plug body 101 having a single sub. The frac plug 100 may further include expansion components including a slip 106, a sealing element 108, and a back-up ring 110. In at least one embodiment, external axial ends 112 of the frac plug 100 may include circumferentially spaced, axial protrusions 114, or “castellations”, extending from the frac plug 100. The castellated axial ends 112 are used in stacking multiple frac plugs 100 in a manner known in the art in some embodiments.

In the illustrated embodiment of FIG. 1, the first sub 102 includes a core (not shown) coupled to an outer sleeve 116. The second sub 104 may include a core (not shown) coupled to an outer sleeve 118. As shown in FIG. 1, the slip 106 may include threads 107 and is positioned between the first and second subs 102, 104 of the frac plug 100. The back-up ring 110 may be positioned between the first and second subs 102, 104 of the frac plug 100, and may be further positioned adjacent the outer sleeve 116 and the slip 106. As shown in FIG. 1, a portion of an outer surface 120 of the outer sleeve 116 is tapered. The slip 106 may include a tapered inner surface (not shown) that contacts the tapered outer surface 120 of the first sub 102.

The sealing element 108 may be positioned within an annular recess 122 in the outer surface 120 of the outer sleeve 116. As shown in FIG. 1, the sealing element 108 is independent of the slip 106. This arrangement allows the sealing element 108 and the slip 106 to be compressed independently. A compression ring 124 may be coupled to the first core using a threaded connection (not shown), retaining the sealing element 108 in place.

Turning now to FIG. 2, FIG. 2 illustrates a side view of the frac plug 100 of FIG. 1 with a cover 200 disposed circumferentially about a portion of the frac plug 100. As illustrated in FIG. 2, the portion of the frac plug 100 covered by the cover 200 includes the slip 106 and the back-up ring 110. In another embodiment, the portion of the frac plug 100 covered by the cover 200 may include at least one expandable component, such as the slip 106. In yet another example embodiment illustrated in FIG. 4, the cover 200 may cover substantially all of the frac plug 100 including the slip 106, the sealing element 108 and the back-up ring 110.

The cover 200 may be a membrane or like covering configured to encompass, enclose, or otherwise cover and prevent one or more of the expansion components from expanding during deployment of and prior to setting the frac plug 100 in a tubular (e.g., casing—not shown) disposed in a wellbore. In one or more embodiments, the cover 200 may be constructed from a plastic material. In another embodiment, the cover 200 may be constructed from a rubber material. In another embodiment, the cover 200 may be a shrink tube. As disposed circumferentially about the frac plug 100, the material may be constructed to provide the cover 200 with a smooth outer surface 202 in order to prevent an occurrence of the frac plug 100 catching on protrusions (not shown) extending from the inner wall (referred to herein as the inner diameter) of the tubular.

The material selected and the thickness of the cover 200 may be determined based at least on the load placed on the frac plug 100 during setting of the frac plug 100. Generally, the load placed on the frac plug 100 to set the frac plug 100 ranges from about 25,000 lbs. to about 35,000 lbs. Accordingly, the material and thickness of the cover 200 may be selected to prevent the expansion components from expanding during deployment of and prior to setting the frac plug 100 in the tubular, and to further tear, split, or otherwise segment into two or more pieces in order to permit the expansion components to expand during the setting of the frac plug 100. For example, in one or more embodiments, the thickness of the cover 200 may be less than 0.010 inches (0.0254 cm).

Prior to and during the deployment or run in of the frac plug 100 in the tubular, the cover 200 may be disposed circumferentially about at least one of the expansion components of the frac plug 100. As shown in the embodiment illustrated in FIG. 2, the portion of the frac plug 100 covered by the cover 200 may include at least the slip 106 and the back-up ring 110. As shown in FIG. 4, the cover 200 may cover substantially all of the frac plug 100 including the slip 106, the sealing element 108 and the back-up ring 110.

During the installation of the frac plug 100, initially, the frac plug 100 may be positioned within a tubular section using a running tool (not shown) that extends through the frac plug 100. The frac plug 100 may be retained on the running tool by a shear ring (not shown) configured to break at a predetermined load and a cylindrical retainer (not shown). The shear ring may be positioned adjacent the second sub 104 and the cylindrical retainer may be positioned adjacent the first sub 102. Once the frac plug 100 reaches the desired location, the running tool begins to compress the frac plug 100 by pulling the shear ring towards the cylindrical retainer and pushing the cylindrical retainer towards the shear ring.

The tapered surface 120 of the outer sleeve 116 may radially expand the slip 106 and the back-up ring 112 as the frac plug 100 is compressed, thereby tearing, splitting, or otherwise segmenting the protective cover into two or more pieces, as shown in FIGS. 3 and 5. As the frac plug 100 is compressed, the threads 107 on the slip 106 contact the tubular section. The threads 107 may engage or “bite” into the inner diameter of tubular section, preventing further movement of the second sub 104 towards the first sub 102. Since the frac plug 100 is being compressed by the running tool, the cylindrical retainer will continue to push the first sub 102 towards the second sub 104. This movement allows the slip 106 and back-up ring 112 to continue to move along the tapered surface 120 of the outer sleeve 116. The continued expansion of the slip 106 allows the threads 107 of the slip 106 to engage with the tubular section, preventing movement of the slip 106 away from the first sub 102 and further retaining the frac plug 100 in position.

Additionally, the compression ring 124 shifts along the external threads of the core of the first sub 102 as the frac plug is compressed, compressing the sealing element 108 and creating a seal between the frac plug 100 and the tubular section. The interface between the compression ring 124 and the core of the first sub 102 may also have a ratcheting effect, where the threads of the compression ring 124 slide over the external threads of the core of the first sub 102 in one direction, but are restricted from moving in the opposite direction by the external threads of the compression ring 124. Accordingly, the ratcheting effect may prevent movement of the compression ring 124 away from the sealing element 108 and the outer sleeve 116.

The slip 106 may engage with the inner diameter of the tubular section when the frac plug 100 is set, securing the frac plug 100 in place. Additionally, the back-up ring 110, having expanded, contacts the tubular section and may prevent extrusion of the sealing element 108. Once the frac plug 100 is set in position, the shear ring breaks when the predetermined load is reached. The running tool is then tripped out of the tubular section.

Once the running tool is removed from the frac plug 100 and the tubular section, a sealing ball (not shown) is dropped down the tubular section. The sealing ball seats against an inner surface (not shown) of the first sub 102, sealing the bore of the frac plug 100. The force of the sealing ball against the first sub 102 of the frac plug 100 may further secure the frac plug 100 in place by shifting the back-up ring 110 and the slip 106 further along the tapered surface 120 of the first sub 102.

Turning now to FIG. 6, FIG. 6 is a flowchart depicting a method 600 for setting a frac plug within a tubular section, according to one or more embodiments disclosed. The method 600 may include covering at least one or more expansion components of the frac plug with a cover, as at 602. The method may also include disposing the frac plug on a running tool, as at 604. The method may further include positioning the frac plug within the tubular section using the running tool, as at 606. The method may also include compressing the frac plug with the running tool such that the cover is segmented and the one or more expansion components engage with the tubular section, retaining the frac plug in position within the tubular section, as at 608.

The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A frac plug, comprising: a first sub having a taper extending along a first portion of an outer surface thereof; a second sub that is threadably engaged with the first sub; a slip circumferentially disposed about the taper of the outer surface of the first sub and adjacent to the second sub; a sealing element circumferentially disposed about the first sub; and a cover disposed circumferentially about at least one of the slip and the sealing element and configured to prevent the at least one of the slip and the sealing element from expanding during deployment of the frac plug in a tubular and to permit the at least one of the slip and the sealing element to expand during setting of the frac plug in the tubular.
 2. The frac plug of claim 1, wherein the cover is disposed circumferentially about the slip and configured to prevent the slip from expanding during deployment of the frac plug in the tubular and to permit the slip to expand during setting of the frac plug in the tubular.
 3. The frac plug of claim 1, wherein the cover is disposed circumferentially about the slip and the sealing element and is configured to prevent the slip and the sealing element from expanding during deployment of the frac plug in the tubular and to permit the slip and the sealing element to expand during setting of the frac plug in the tubular.
 4. The frac plug of claim 1, further comprising a back-up ring disposed between the first sub and the second sub.
 5. The frac plug of claim 4, wherein the cover is disposed circumferentially about the slip and the back-up ring and is configured to prevent the slip and the back-up ring from expanding during deployment of the frac plug in the tubular and to permit the slip and the back-up ring to expand during setting of the frac plug in the tubular.
 6. The frac plug of claim 4, wherein the cover is disposed circumferentially about the slip, the sealing element, and the back-up ring and is configured to prevent the slip, the sealing element, and the back-up ring from expanding during deployment of the frac plug in the tubular and to permit the slip, the sealing element, and the back-up ring to expand during setting of the frac plug in the tubular.
 7. The frac plug of claim 1, wherein the cover is constructed from a plastic material.
 8. The frac plug of claim 1, wherein the cover is constructed from a rubber material.
 9. The frac plug of claim 1, wherein the cover is a shrink tube.
 10. A frac plug, comprising: a plug body; a plurality of expansion components axially spaced from one another and circumferentially disposed about the plug body, each of the expansion components configured to expand radially outward from the plug body in response to a compressive force applied by a setting tool; and a cover disposed circumferentially about at least one expansion component of the plurality of expansion components and configured to prevent the at least one expansion component from expanding during deployment of the frac plug in a tubular and to permit the at least one expansion component to expand during setting of the frac plug in the tubular with the setting tool.
 11. The frac plug of claim 10, wherein the cover is disposed circumferentially about each expansion component of the plurality of expansion components.
 12. The frac plug of claim 10, wherein the plurality of expansion components includes: a slip; a sealing element; and a back-up ring disposed between the slip and the sealing element.
 13. The frac plug of claim 12, wherein the cover is disposed circumferentially about the slip and the back-up ring.
 14. The frac plug of claim 10, wherein the cover is constructed from a plastic material or a rubber material.
 15. A method for setting a frac plug within a tubular section, the method comprising: covering at least one or more expansion components of the frac plug with a cover; disposing the frac plug on a running tool; positioning the frac plug within the tubular section using the running tool; and compressing the frac plug with the running tool such that the cover is segmented and the one or more expansion components engage with the tubular section, retaining the frac plug in position within the tubular section.
 16. The method of claim 15, wherein the one or more expansion components include at least one of a slip, a sealing element, and a back-up ring.
 17. The method of claim 16, wherein the one or more expansion components include the slip, the sealing element, and the back-up ring.
 18. The method of claim 16, wherein the one or more expansion components include the slip and the back-up ring.
 19. The method of claim 15, wherein the cover is constructed from a plastic material.
 20. The method of claim 15, wherein the cover is constructed from a rubber material. 